POLYPHASE INDUCTION MOTOR HAVING A FERROMAGNETIC ROTOR PLATE

Abstract: A polyphase induction motor (10) is disclosed having two electromagnet arrangements (12, 14), each of the electromagnet arrangements (12, 14) having pole pieces (24, 26) with corresponding polar faces (27). The two electromagnet arrangements (12, 14) are arranged such that the polar faces (27) of the two electromagnet arrangements (12, 14) are in a mirrored facing relationship each other. A gap (66) is therefore defined between the facing polar faces (27) of the electromagnet arrangements (12, 14). A substantially planar ferromagnetic conductor plate (16) is disposed within the gap (66), and rotates about the central axis (68) of the motor (10).

Description: POLYPHASE INDUCTION MOTOR HAVING A FERROMAGNETIC ROTOR PLATE FIELD OF THE INVENTION The present invention relates generally to motors, and more particularly to polyphase induction motors. BACKGROUND OF THE INVENTION A.C. electrical motors are widely used in commercial, industrial, domestic and other applications where rotating power is required. A typical type of this motor is the an A.C. induction motor known commonly as a squirrel cage motor. One drawback of the squirrel cage motor however is the size of the motor. Another known type of induction motor is the shaded pole motor. The shaded pole motor overcomes the size problem by utilizing an aluminum or copper disk as a rotor. More specifically, an electromagnet is powered by alternating current from a generator. The magnet produces a varying flux through the aluminum disk rotor. On e half of the magnet pole is covered with an aluminum plate which causes the disk to rotate A problem with the shaded pole motor, however, is that design is not suitable for a practical high efficiency motor. Another problem with the shaded pole motor is that it does not provide necessary high forces. Therefore, a need exists for an induction motor having a rotor disk that provides high forces. A need also exists for an SUBSTITUTE SHEET (RULE 36) SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to overcome one or more disadvantages and limitations of the prior art. A significant object of the present invention is to provide an induction motor having a rotor disk. Another object of the present invention is to provide an induction motor that is efficient and provides high forces. Another object of the present invention is to provide an induction motor that is easily manufactured. According to a broad aspect of the present invention, a polyphase induction motor has two electromagnet arrangements, each of the electromagnet arrangements having pole pieces with corresponding polar faces. The two electromagnet arrangements are arranged such that the polar faces of the two electromagnet arrangements are in a mirrored facing relationship each other. A gap is therefore defined between the facing polar faces of the electromagnet arrangements. A substantially planar ferromagnetic conductor plate is disposed within the gap, and rotates about the central axis of the motor. A feature of the present invention is to provide an induction motor that is brushless and does not use permanent magnets. Another feature of the present invention is to provide an. induction motor that is easily manufactured. Another feature of the present invention is that the motor provides high forces. Another object of the present invention is that the motor design may be used as a generator or alternator by simply changing the electrical system driver. These and other objects, advantages and features of the present invention will become readily apparent to those skilled in the art from a study of the following description of an exemplary preferred embodiment when read in conjunction with the attached drawing and appended claims. BRIEF DESCRIPTION OF THE DRAWING Figure 1 is a side cross-sectional view of one embodiment of the induction motor of the present invention; Figure 2 is a top cross-sectional view of an embodiment of the induction motor shown in Figure 1 ; Figure 3 is a side view of one of the electromagnets of the induction motor of the present invention; Figure 4 is an electromagnet configuration for an alternative embodiment of the induction motor; and Figure 5 is an electromagnet configuration for a second alternative embodiment of the induction motor. DESCRIPTION OF AN EXEMPLARY PREFERRED EMBODIMENT Referring now to Figures 1 and 2, a polyphase induction motor 10 is shown. The motor includes an upper electromagnet arrangements 12, a lower electromagnet arrangement 14, and a conductor rotor 16 made of ferromagnetic material. The upper electromagnet arrangement and the lower electromagnet arrangement are disposed in a mirrored, symmetrical relationship to each other, with the conductor rotor disposed intermediate the two arrangements. In the embodiment shown, each of the arrangements include eight electromagnets 18. Other quantities of electromagnets may be used however, for certain applications, it is preferable to use electromagnets in integral multiples of four. The electromagnets are comprised of cores 20 and coils 28. One of the electromagnet cores 20 is best shown in Figure 3. The electromagnet 20 preferably includes an aperture 22 in the center of the core and is preferably laminated. Each of the electromagnets has a first pole piece 24 and a second pole piece 26. The electromagnets further define polar faces 27. The polar faces may have a trapezoidal, rectangular or square cross-section. The coils 28 used in the electromagnet arrangements of the induction motor will vary according to the desired application of the motor. By way of example, referring to Figure 1 , a first coil 28 surrounds the first and second pole pieces of each electromagnet core. The electromagnet assembly may further includes a plurality of second coils (not shown). Assuming there are n electromagnets in the electromagnet assembly, each of the second coils may surround the first pole piece of an nth electromagnet and the second pole piece of an nth-1 electromagnet. Referring now to Figure 4, an electromagnet configuration for an alternative embodiment of the induction motor is shown. This embodiment uses at least three electromagnets, each having a first and a second pole piece. A first coil 30 surrounds the first electromagnet first 38 and second 40 pole pieces and a second coil 32 surrounds the second electromagnet first 42 and second 44 pole pieces. Opposite currents are applied to the first and second coils. A third coil 34 surrounds the the first electromagnet second pole piece 40 and the second electromagnet first pole piece 42. A fourth coil 36 surrounds the second electromagnet second pole s piece 44 and the third electromagnet first pole piece 46. Opposite currents are applied to the third and fourth coils. This pattern is repeated for the number of desired electromagnets for any particular application. lo Referring now to Figure 5, the configuration of a three phased current embodiment of the induction motor is shown. The electromagnet arrangement includes at least three electromagnets, each having a first and a second pole piece. A first coil 50 surrounds the first electromagnet first 56 and i5 second 58 pole pieces and the second electromagnet first pole piece 60, a second coil 52 surrounds the first electromagnet second pole piece 58 and the second electromagnet first 60 and second 62 pole pieces, and a third coil 54 surrounds the second electromagnet first 60 and second 62 pole pieces and 20 the third electromagnet first pole piece 64. The current applied to the first coil 50 is preferably at 240 degrees, the current applied to the second coil 52 is at 0 degrees, and the current applied to the third coil 54 is at 120 degrees. This pattern is also repeated for the number of desired 25 electromagnets. Referring back to Figure 1 , the first electromagnet assembly and the second electromagnet assembly are assembled in symmetrical relationship to each other. The 3o first (or upper) and second (or lower) electromagnet assemblies are positioned such that the polar faces of the first electromagnet assembly are in a mirrored facing relationship with the pole faces of the second electromagnet assembly, defining a gap 66 therebetween. The ferromagnetic conductor rotor disk 16 is disposed in the gap 66 between the pole faces of the first and second electromagnetic assemblies 12, 14 and rotates about a central axis 68 of the motor. Referring now to Figures 1 and 2, the assembly of the motor 10 is described. The motor includes a first electromagnet assembly frame 70 and a second electromagnet assembly frame 72, corresponding to the respective first and second electromagnet assemblies. The electromagnetic assembly frames are each substantially planar disks with n number of chambers 74 in the disk corresponding to the n number of electromagnets in the corresponding electromagnet assembly. The chambers are arranged symmetrically around the central axis 68 of the motor such that when assembled, the electromagnets will be disposed symmetrically around the central axis. Each of the electromagnets is placed in a chamber during assembly. Each of the electromagnets of the first electromagnet assembly 12 are disposed in the chamber such that the electromagnet is suspended below the first electromagnet assembly frame. Each of the electromagnets of the second electromagnet assembly 14 are assembled such that the electromagnet is supported above the second electromagnet frame. The electromagnet frames include a positioning holes 76 aligned with each chamber. Pins are placed through the positioning holes after the electromagnets are disposed in the chamber in order to hold the electromagnets in position. The first and second electromagnet frames 70, 72 are axially spaced from one another by a spacer member 76. The spacer is dimensioned to maintain the upper and lower electromagnet assemblies at a proper distance from each other. The electromagnet assemblies are disposed intermediate a first end plate 78 and a second end plate 80. The two end plates fastened together by a plurality of endplate fasteners 82. As previously described, the rotor disk 16 is disposed in the gap 66 between the pole faces of the first and second electromagnet assemblies. The disk is assembled so as to rotate about the central axis of the motor. More specifically, the rotor disk 16 is press fit onto a rotor hub 84. A shaft 86 extends though the center of the rotor disk and through the center of the end plates and aligned with the central axis of the motor. Bearings 88 surround the shaft at the point where the shaft extends through the end plates. It is to be understood that, with appropriate electronic drivers, the induction motor can be linear or rotary and can be made reversible to function as an actuator. The motor may also be used as an induction generator or as an induction alternator. The use of the motor as a generator or alternator requires only the modification of the electrical system driver such that the power generated or recovered is channeled to a battery or power grid. The operation of the motor as a motor requires that the magnetic wave speed is greater than the tangential speed of the rotor. In comparison, the operation of the motor as an alternator requires that the magnetic wave speed is less than the tangential speed of the rotor. When the magnetic wave speed is the same as the tangential speed of the rotor there is no transfer between electrical energy and mechanical energy. If the device is connected to a source of EMF that defines alternating voltages of constant amplitude, the electrical currents will flow spontaneously in the direction required for motor operation or alternator operation. There has been described hereinabove an exemplary preferred embodiment of the induction motor according to the principles of the present invention. Those skilled in the art may now make numerous uses of, and departures from, the above-described embodiments without departing from the inventive concepts disclosed herein. Accordingly, the present invention is to be defined solely by the scope of the following claims.

Claims: THE CLAIMS I claim as my invention: 1 1. A polyphase induction motor comprising: 2 a first electromagnet arrangement, said 3 arrangement having a first plurality of polar faces; 4 a second electromagnet arrangement, said second 5 electromagnet arrangement having a second plurality of polar 6 faces, said second plurality of polar faces being in a mirrored 7 facing relationship to said first plurality of polar faces, such 8 that a gap is defined between said first and second plurality of 9 polar faces; and l o a substantially planar ferromagnetic conductor l i plate disposed within said gap. 1 2. A polyphase induction motor in accordance with 2 Claim 1 wherein said first electromagnet arrangements 3 comprise a first electromagnet having a first electromagnet 4 first pole piece and a first electromagnet second pole piece and 5 a second electromagnet having a second electromagnet first 6 pole piece and a second electromagnet second pole piece. 1 3. A polyphase induction motor in accordance with 2 Claim 2 wherein said electromagnet arrangements further 3 comprise a primary first coil surrounding said first 4 electromagnet first and second pole pieces and a secondary 5 first coil surrounding said second electromagnet first and 6 second pole pieces. 1 4. A polyphase induction motor in accordance with 2 Claim 3 wherein said electromagnet arrangements further 3 comprise a second coil surrounding said first electromagnet 4 second pole piece and said second electromagnet first pole 5 piece. 5. A polyphase induction motor in accordance with Claim 1 wherein said electromagnets of said first and second electromagnet arrangements are arranged symmetrically around a central axis and further wherein said rotor plate rotates about said axis. 6. A polyphase induction motor in accordance with Claim 4 wherein a first current is applied to said first coils and a second current is applied to said second coil, said second current being 180 degrees out of phase from said first current. 7. A polyphase induction motor in accordance with Claim 2 wherein said electromagnet arrangements further comprise a third electromagnet having a third electromagnet first pole piece and a third electromagnet second pole piece. 8. A polyphase induction motor in accordance with Claim 7 wherein said electromagnet arrangements further comprise a first coil surrounding said first electromagnet first and second pole pieces and said second electromagnet first pole piece, a second coil surrounding said first electromagnet second pole piece and said second electromagnet first and second pole pieces, and a third coil surrounding said second electromagnet first and second pole pieces and said third electromagnet first pole piece. 9. A polyphase induction motor in accordance with Claim 8 wherein the current applied to said first and second coils are 120 degrees out of phase from each other and the current applied to said second and third coils are 120 degrees out of phase from each other. 10. A polyphase induction motor comprising: a first electromagnet arrangement, said arrangement comprising at least two sets of electromagnets, said sets comprising a first electromagnet and a second 5 electromagnet, each of said first and second electromagnets 6 having a first pole piece and a second pole piece and a first coil 7 surrounding said first and second pole pieces; 8 a second electromagnet arrangement identical to said 9 first electromagnet arrangement, wherein said second 10 electromagnet arrangement is in a mirrored facing relationship l i to said first electromagnet arrangement, defining a gap 12 between the electromagnet arrangements; and 13 a ferromagnetic conductor rotor disposed in said gap. 1 1 1 . A polyphase induction motor in accordance with 2 Claim 10 wherein said electromagnets of said first and second 3 electromagnet arrangements are arranged symmetrically 4 around a central axis and further wherein said rotor rotates 5 about said axis. 1 12. A polyphase induction motor in accordance with 2 Claim 10 wherein said rotor is substantially planar. 1 13. A polyphase induction motor in accordance with 2 Claim 10 wherein said electromagnet arrangements further 3 include a second coil surrounding said first electromagnet 4 second pole piece and said second electromagnet first pole 5 piece. 1 14. A polyphase induction motor in accordance with 2 Claim 13 wherein a first current is applied to said first coil and 3 a second current is applied to said second coil, said second 4 current being 180 degrees out of phase from said first current. 1 15. A polyphase induction motor in accordance with 2 Claim 10 wherein said electromagnets are laminated.

Inventors: MORINIGO FERNANDO, MORINIGO, FERNANDO
Applicants: AURA SYSTEMS INC, AURA SYSTEMS, INC.
Application year: 1996
Main classification: H02K17
IPC codes: H02K17