JPH0459478A - Electric motor - Google Patents

Abstract

PURPOSE:To operate an electric motor continuously and properly even if a failure partially occurs by providing multiple rotors transferring the rotation to an output shaft respectively and stators mated with the rotors in a housing, and separately providing driving circuits for individual pairs of the rotors and stators. CONSTITUTION:An electric motor 7 has two rotors 16, 17 in a housing 15, and they are fitted to an output shaft 9. Stators 18, 19 mated with the rotors 16, 17 are fitted at the positions corresponding to the rotors 16, 17 on the inner periphery of the housing 15. A driving circuit 20 is provided for the pair of the rotor 16 and stator 18, and a driving circuit 21 is provided for the pair of the rotor 17 and stator 19 respectively. A control device 10 has motor control means 24, 25 for the circuits 20, 21 separately, the control means 24 controls the circuit 20 based on the steering information from a rear wheel steering angle determining means 26, and the control means 25 controls the circuit 21 respectively. Both circuits 20, 21 are driven under the normal condition.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an electric motor.

[Conventional technology]

Electric motors are widely used in various industrial fields because of their excellent controllability. The types of motors are roughly divided into DC motors and AC motors depending on the type of power source used, and there are various types of these motors. Typically, an electric motor includes a rotor connected to an output shaft and a stator that causes electromagnetic induction to occur between the rotor and the rotor. Torque is generated in the rotor and actuated. In the case of a general DC motor, the rotor is composed of an armature consisting of an iron core, an armature coil fitted into a slot in the iron core, and a commutator, and the stator is made up of a permanent magnet, an electromagnet, etc. It is often composed of a magnetic field. Furthermore, in the case of an AC motor, the rotor is constituted by a field, and the stator is constituted by an armature, as opposed to a DC motor.

[Problem to be solved by the invention]

By the way, in the case of a conventional electric motor, the rotor, stator, and their drive circuit are composed of only one pair. Therefore, once a failure occurs in the motor or drive circuit, it becomes impossible to continue operating the device driven by this failure. However, even in such a case, if the motor can be operated appropriately, the apparatus does not have to be forced to stop. This prevents deterioration of production efficiency, for example, in the case where manufacturing equipment is driven by a motor. Further, when a motor is used in a drive device or a steering device of an automobile where safety is particularly required, dangerous situations due to motor failure can be avoided. One possible solution to this problem is, for example, to mount a plurality of motors so that even if one breaks down, the device can be moved by another motor. However, with this method, not only the cost increases significantly, but also the mechanism of the entire device becomes complicated. Also,
Increasing the size of the device due to securing mounting space is also a problem. Therefore, it is an object of the present invention to provide an electric motor that is configured to be able to continue to operate properly even if a part of the motor malfunctions.

[Means to solve the problem]

In order to solve the above problems, the present invention takes the following technical measures. That is, the electric motor of the present invention includes, in the housing,
It includes a plurality of rotors, each of which can transmit rotation to an output shaft, and a stator provided in pairs with each rotor, and a drive circuit for each pair of rotor and stator is separately provided. It is set.

[Operation and effects of the invention]

An electric motor can basically be configured by a pair of rotor and stator, and a drive circuit. In the case of the electric motor of the present invention, a plurality of sets of rotors and stators are provided, and their drive circuits are set separately for each set. Further, each set of rotors transmits rotation to the output shaft. In other words, the electric motor of the present invention has a structure that includes multiple mechanisms that can independently operate the motor, so that even if some rotor, stator, etc. have an abnormality, other rotors, etc. can be operated. Therefore, the safety and convenience of using the electric motor are greatly improved.

[Explanation of Examples]

Embodiments of the present invention will be described below with reference to the drawings. In this example, a case where the present invention is applied to an electric motor for driving a four-wheel steering system of an automobile as shown in FIG. 1 will be described. The illustrated four-wheel steering device includes a front wheel steering mechanism 2 that steers the front wheels 1 through steering operation, and a rear wheel steering mechanism 4 that steers the rear wheels 3 under predetermined conditions.
The rear wheel steering mechanism 4 is configured to be driven by a motor. The rear wheel steering mechanism 4 includes a rack par 5 movable in the vehicle width direction and a pinion gear 6 meshed with the teeth 5a of the rack par 5. The signal is transmitted to the pinion gear 6. When the pinion gear 6 is rotated, the rack par 5 is moved in the vehicle width direction, and the movement of the rack par 5 steers the rear wheels 3 connected to both ends thereof in a predetermined direction. The electric motor 7 is disposed in front of the rear wheel steering mechanism 4 with the reduction gear 8 interposed therebetween, and is connected to its output shaft 9 or the reduction gear 8. Further, the electric motor 7 is controlled by a control device 10 constituted by a microcomputer or the like. As shown in FIG. 2, control information from a vehicle speed sensor 11, a steering angle sensor 12, a motor rotation speed sensor 13, etc. is sent to this control device IO. The control device IO is
The magnitude of lateral G (lateral acceleration) generated during steering is calculated from the vehicle speed information and steering angle information, and based on this, the steering direction and amount of steering of the rear wheels 3 are determined. In this case, the control device 10 controls the control device 10 so that when the magnitude of the lateral G is small, the rear wheels 3 are steered in an opposite phase (in the opposite direction) with respect to the front wheels l with a relatively large steering angle; When the value is larger than a predetermined value, the rear wheels 3 are steered in the same phase (same direction) as the front wheels 1 with a small steering angle.
Controls the rotation of the electric motor 7. When lateral G is small,
This is generally a case where the vehicle turns at a low speed, and at this time, by steering the rear wheels 2 in opposite phases, the turning radius of the vehicle can be reduced and the turning ability can be improved. In addition, when changing lanes or turning during medium/high speed driving, the lateral G increases, but in this case, by steering the rear wheels 3 in the same phase, the vehicle's sideslip is suppressed and driving stability is improved. It can be improved. Further, in FIG. 1, reference numeral 14 is an electromagnetic brake for the electric motor 7. As shown in FIG. This electromagnetic brake 14 prevents overrun due to inertia, accurately stops the electric motor 7 at a predetermined rotation speed, and improves steering accuracy. Incidentally, in the electric motor of the present invention, a plurality of sets of rotors and stators are provided, and a drive circuit is separately set for each set. As shown in FIG. 1, the electric motor 7 in this example includes two rotors 16 and 17 within the housing 15, which are fitted around the output shaft 9. Furthermore, stators 18.19 for each rotor 16.17 are attached to the inner periphery of the housing 15 at positions corresponding to each rotor. Furthermore, as shown in FIG. 2, the drive circuit 21
Alternatively, one is provided for each pair of rotor 17 and stator 19. The illustrated electric motor 7 is a DC motor, and the rotor 16.17 is constituted by an armature, while the stator 18.19 is constituted by a field such as a permanent magnet or an electromagnet. Ru. Further, in the figure, numerals 22a and 23a are commutators provided at the ends of the armature, and numerals 22b and 23b are brushes. As described above, the electric motor 7 is controlled by the control device IO. In this example, as shown in FIG. 2, the control device 10 includes separate motor control means 24 and 25 for each of the drive circuits 20 and 21, and receives steering information from the rear wheel turning angle determining means 26. Based on the motor control means 24
The drive circuit 20, the motor control means 25, and the drive circuit 21 are controlled respectively. In this case, in the normal state, each drive circuit 20i21 is driven together. In the above configuration, even if a failure occurs in a part of the electric motor, the motor can be operated. Since the electric motor 7 includes two sets of a rotor, a stator, and a drive circuit, even if any abnormality occurs in the rotor, stator, or drive circuit of one set, the rotation of the other set is stopped. Child,
The stator and drive circuit can operate the motor. In this example, if an abnormality occurs in one set of rotor, stator, and drive circuit, the fail-safe circuit 27 provided in the control device 10 cuts off the drive current to the drive circuit in which the failure has occurred. At the same time, the other drive circuit is energized and the motor is operated to return the rear wheel 3 to the neutral position. Furthermore, after this, all drive current to the motor drive circuit is cut off, and the 2WS state in which the rear wheels 3 are not steered is maintained. Further, in this case, a warning lamp provided in the driver's cabin may be turned on to alert the driver. With a normal electric motor, if the motor breaks down while the rear wheels 3 are being steered, it will not be possible to return the rear wheels 3 to the neutral position. If this occurs in an anti-phase steering state where the steering wheel is turned significantly, normal driving becomes impossible. However, in this example, as described above, even if a failure occurs in the electric motor 7, it can still be operated to return the rear wheel 3 to the neutral position and guide it to the safe side. Therefore, the failsafe is sufficient and safety is greatly increased. Note that an abnormality in the motor can be detected by the occurrence of abnormal current in the rotor, drive circuit, or the like. Furthermore, in the above, the rear wheel steering mechanism 4 is not moved after the rear wheels 3 are returned to the neutral position, but even after a failure occurs, the motor is operated and the rear wheel steering mechanism 4 is operated as before. You can also build a system to make it work. By the way, the scope of the present invention is not limited to the above-described embodiments. For example, as shown in FIG.
7 may be arranged in parallel within the housing 15. Also, in this example, a pinion gear 28, 29 is attached to the shaft of each rotor 16, 17, and a gear 30 that meshes with each of the pinion gears 28, 29 is attached to the output shaft 9 to extract rotation. By making the gear 30 larger in diameter than the pinion gear 2829, it is provided with a deceleration function. Therefore, it is not necessary to set the reduction ratio of the reduction gear 8 to a large value. Further, the housing 15 includes each rotor 16 .
The left and right housing portions 15a and 15b that house the housing 17 are integrally formed. Therefore, compared to the case where the housing parts 15a and 15b are configured separately, it is easier to achieve accuracy in the distance between the axes of the left and right rotor axes, and the rigidity of the housing and installation workability are also improved. do. Furthermore, three or more sets of rotors, stators, and drive circuits may be provided, and in this case, safety is further improved. Furthermore, the present invention can be applied not only to DC motors but also to AC motors, as well as to various types of electric motors.

[Brief explanation of drawings]

Fig. 1 is a diagram schematically showing the overall configuration of a four-wheel steering device according to an embodiment of the present invention, Fig. 2 is a system block diagram of the embodiment, and Fig. 3 is a diagram showing another embodiment. be. 9... Output shaft, 15... Housing, 16.17.
...Rotor, 18.19...Stator, 20.21...
・Drive circuit.

Claims (1)

[Claims] (1) A housing includes a plurality of rotors, each of which can transmit rotation to an output shaft, and a stator set to form a pair with each rotor, and each pair of a rotor and a stator. An electric motor characterized in that drive circuits for each are set separately.