Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-08-07
2003-04-01
Karl, Tamai I (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S181000, C310S263000
Reexamination Certificate
active
06541887
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a motor-generator, which is comprised of a rotor of permanent-magnet pieces supported for rotation in a stator housing, a stator surrounding around an outside periphery of the rotor, and magnet coils arranged at axially opposing ends of the stator, each to each end, to keep a voltage steady.
2. Description of the Prior Art
Modern advanced permanent magnets of high performance have become much employed on a rotor of a motor-generator. Moreover, as the motor-generator having the rotor structure of permanent magnets is high in efficiency of electromechanical energy conversion and simple in construction, its use has recently grown in industrial machines and instruments of various kinds. Then, much research and development have continued to make the motor-generator compact or slim in construction, with even high performance and high power output, and correspondingly necessitated a diversity of parts and components.
In order to increase a torque at low speed in operation of the conventional motor-generator, it is effective to increase the strength of the magnetic field of the stator around the rotor, thereby raising the torque. With the motors, thus, increasing well the torque causes the increase of electromotive force at a low speed, contributing to the provision of commercially viable power source for machines. Among the rotating machinery employing the permanent-magnet rotor is, for example a permanent-magnet rotating machine disclosed in Japanese Patent Laid-Open No. 272850/1987. The prior permanent-magnet rotating machine has a rotor in which permanent magnets are arranged and containers are provided to contain therein magnetic material that is allowed to flow radially owing to the revolution of the rotor to thereby form magnetic pole pieces.
Moreover, another prior art of an a-c motor-generator capable of developing a high-power output is disclosed in Japanese Patent Laid-Open No. 236260/1995, in which a magnetic flux density is controlled in proportion to the speed in revolutions per minute (rpm) of the rotor to adjust properly an amount of the generated amperes or voltages. A control ring is arranged between the rotor and the stator for rotation relatively of them and further a permeable member is provided in such a manner as to come in and out contact with the control ring.
Further disclosed in Japanese Patent Laid-Open No. 261996/2000, which is co-pending application of the present inventor, is a high-torque motor-generator in which the permeable member is made of amorphous alloys to allow the magnetic forces to pass effectively through the small spaces, thereby increasing the torque at low speed in rpm of the rotor. The prior motor-generator is comprised of permeable members arranged in juxtaposition around a rotor shaft with nonmagnetic members being each interposed between any two adjoining permeable pieces, a magnetic path core arranged surrounding the outside periphery of the permeable members, platy permanent-magnets arranged around the outside periphery of the magnetic path core, and nonmagnetic reinforcing member fixed on the outside periphery of the permanent-magnets.
In the meantime, as most automotive electric equipments are designed to require either 12V or 24V, the automotive alternators need to have the generation characteristic capable of feeding the electric power matching to the voltage recited just above. Nevertheless, the d-c power of either 12V or 24V is too low to operate other industrial machinery such as auxiliaries mounted on an automobile, in which much power is required for their operation, thus apt to be much subject to transmission loss in the associated wiring. Moreover, a major problem exists in which too thick in cross section of conductor is necessitated for windings and wirings. To cope with this, the alternator is needed producing not only the electric power of low voltage matching to the voltage required for the automotive electric equipments but also another electric power having high tension adapted to energize the auxiliaries, industrial appliances, and so on. The high tension of the generated electric power reduces the transmission loss in the wiring, rendering the conductor such as windings thin in cross section, thereby making the alternator itself compact or slim in construction.
With the permanent-magnet motor-generator, the permanent magnet is fixed in magnetic flux density and accordingly unchanged in magnetic force, either at low speed or high speed. Nevertheless, the voltage and correspondingly the output of the motor-generator rises in proportion to the increase of the rpm of the rotor. Thus, the motor-generator designed to produce the desired output voltage when the rotor is at low speed comes to yield too high voltages to control them properly. As opposed to the event stated just earlier, the way to raise the output voltage at a low speed needs to either make the permanent magnet large in size or increase the current and also increase the number of loops or turns in the winding to intensify the strength of the magnetic field at the stator side with the result of yielding great torque. However, the output voltages at the high speed also become too high to control them adequately. To increase the torque in the motor-generator, moreover, it is needed to make the conductor wound on the stator core heavy in cross section to carry large current, thereby intensifying the magnetic force in the stator.
SUMMARY OF THE INVENTION
It is a primary object of the present invention to overcome the problems stated earlier and to provide a motor-generator having a voltage stabilizer, in which windings laid in slots of a stator core are grouped into more than one winding set that are connected in series and/or parallel to continue producing a desired output voltage independently of the variations of the rotor speed in rpm, and further in which a cylindrical magnetic path extends axially of the rotor in opposition to electromagnet coils arranged at axially opposing ends of the rotor, each to each end, and conduction to the electromagnet coils is controlled in such a manner as to intensify magnetic force in permanent-magnet pieces when the output voltage is low while weaken the magnetic force when the output voltage is high, thereby always ensuring the desired output voltage.
Another object of the present invention is the provision of a motor-generator raised in torque at low speed, characterized in that the electromagnets are installed at axial opposing ends of a rotor mounted on a rotor shaft, each to each end, to lead magnetic forces created by the electromagnets to the rear of a permanent magnet through a permeable member, adding the magnetic forces to magnetic forces developed in the permanent magnet to thereby increase the torque at low speed, and in that the revolving direction of the magnetic force developed from the permanent magnet is made in a loop unlike the whirl direction of the magnetic fields created by the electromagnets to compensate for a small area in the electromagnet core where the magnetic flux is allowed to pass through there, thereby ensuring the magnetic flux density enough to control the magnetic force by either adding or subtracting the magnetic forces of the electromagnets to or from the magnetic force of the permanent magnet, and further in that permanent-magnet pierces are circumferentially arranged with nonmagnetic pieces being each interposed between any two adjoining permanent-magnet pieces, thereby forming a multipolar cylindrical permanent-magnet construction where unlike poles alternate circularly, and an electromagnet core superior in magnetic permeability is arranged inside the permanent-magnet construction, thus allowing the magnetic flux from the electromagnets to flow through there.
A further another object of the present invention is to provide a motor-generator in which electromagnets are arranged at axially opposing ends of a rotor around a rotor shaft, whereby magnetic forces created by the electromagnets are led
Browdy and Neimark , P.L.L.C.
Karl Tamai I
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