Controlled rotor motor

Abstract

An electric motor for driving a mechanical load at variable speed and constant torque includes a stationary housing containing a magnetic field rotor driven by alternating current and surrounding a drive rotor. The rotors rotate in opposite direction when the drive rotor is coupled to a load. The motor can be of induction or synchronous type. The means for adjustably varying retardation of the field rotor and consequently the speed of the drive rotor .[.may be by.]. .Iadd.is .Iaddend.a direct current energized magnetic coercive force clutch mechanically coupled to the field rotor .[.or by other electromechanical means connected in circuit with the field rotor.]. .Iadd.to provide constant output torque throughout the speed range of the drive rotor.Iaddend..

The invention claimed is: 
     
       1. An electric motor for driving a mechanical load comprising: a stationary housing; a first rotatable means .[.wholly comprising the secondary of said motor.]. extending axially of said housing and being rotatable in a selected direction for driving said load; a second rotatable means .[.having slotted laminations and field coil windings therein.]. surrounding said first rotatable means and extending axially in said housing for magnetically rotating said first rotatable means in one direction when said first rotatable means coupled to said load, a hardened high hysteresis steel ring being mounted on said second rotatable means for rotation therewith; said second rotatable means beng rotatable in a direction opposite to that of said first rotatable means; control means comprising a plurality of electromagnets mounted on said stationary housing .Iadd.in juxtapostion to said steel ring .Iaddend.for retarding the rotation of said second rotatable means to vary the speed of rotation of said first rotatable means in said selected direction.[...]..Iadd., while maintaining substantial constant driving torque to said load at all rotational speeds of said first rotatable means. .Iaddend. 
     
     
       2. The electric motor according to claim 1 wherein .[.said field coil windings are energized by alternating current.]. said electromagnets .[.being.]. .Iadd.are .Iaddend.energized by direct current. 
     
     
       3. The electric drive motor according to claim 1 wherein said electromagnets are mounted on said stationary housing and spaced a selected distance from said hardened steel ring. 
     
     
       4. The electric drive motor according to claim 1 wherein said electromagnets are alternately arranged north and south pole pieces. .[.5. An electric motor for driving a mechanical load comprising: a stationary housing; a first rotatable means wholly comprising the secondary of said motor extending axially of said housing for driving said load; a second rotatable means energizable by alternating current circumferentially surrounding said frist rotatable means and extending axially in said housing for magnetically rotating said first rotatable means in one direction when coupled to said load, while said second rotatable means rotates by magnetic reaction in an opposite direction when energized by alternating current; and control means surrounding a portion of said second rotatable means for adjustably retarding rotation of said second rotatable means thereby varying the speed of rotation of said first rotatable means in said one direction..]. .[.6. An electric motor as defined in claim 5, wherein said control means is arranged to vary the speed of rotation of said first rotatable means at will from zero revolutions per minute up to the maximum rated drive speed of said first rotatable means, whereby said driving torque applied to said load is constant at rotational speeds of said first rotatable means and whereby the difference in rotational speeds between said first and said second rotatable means is constant at all speeds of rotation of said first rotatable means..]. .[.7. An electric motor as defined in claim 6 further comprising a hardened steel ring and wherein said control means comprises a plurality of stationary electromagnets carried by said housing the hardened steel ring being integral with the said second rotatable means and arranged to react magnetically with a stationary portion for selectively and adjustably retarding rotation of said second rotatable 
     
     
        means to drive said first rotatable means in said one direction..]. 8. An electro motor as defined in claim .[.7.]. .Iadd.1.Iaddend., wherein said first rotatable means is a squirrel cage and constitutes the rotor of an 
     
     
        induction motor. 9. An electric motor as defined in claim .[.7.]. .Iadd.1 .Iaddend.wherein said first rotatable means is of a salient pole type to constitute the rotor of a synchronous motor. .[.10. An electric motor as defined in claim 7, wherein said stationary portion is an assembly of coils wound on cores of soft iron and wherein said rotatable portion is a 
     
     
        ring of high hysteresis loss magnetic material..]. 11. An electric motor as defined in claim .[.10.]. .Iadd.1.Iaddend., wherein said control means further comprises: a source of direct current, and a variable resistance connected in series with said source of direct current for varying the direct current passing through said coils to vary the retardation of said second rotatable means and therefore the rotational speed of said first rotatable means.  .[.12. An electric motor as defined in claim 5 wherein said motor is connected to a source of alternating current of fixed frequency wherein said motor can provide a variable speed constant torque output..].