Motor for high temperature applications
A high temperature motor has a stator with poles formed by wire windings, and a rotor with magnetic poles on a rotor shaft positioned coaxially within the stator. The stator and rotor are built up from stacks of magnetic-alloy laminations. The stator windings are made of high temperature magnet wire insulated with a vitreous enamel film, and the wire windings are bonded together with ceramic binder. A thin-walled cylinder is positioned coaxially between the rotor and the stator to prevent debris from the stator windings from reaching the rotor. The stator windings are wound on wire spools made of ceramic, thereby avoiding need for mica insulation and epoxy/adhesive. The stator and rotor are encased in a stator housing with rear and front end caps, and rear and front bearings for the rotor shaft are mounted on external sides of the end caps to keep debris from the motor migrating into the bearings' races.
1. A high temperature motor comprising:
a stator in a cylindrical shape on a motor axis having poles formed by wire windings on an inner circumference thereof, said wire windings being wound on respective wire spools held in place in respective slots formed on the inner circumference of said stator;
a rotor mounted on a rotor shaft having poles formed by magnetic material and being positioned coaxially within an inner volume defined in said stator;
a thin-walled cylinder positioned coaxially between said rotor and said stator for physically separating them,
wherein said stator and said rotor are built up from a stack of magnetic-alloy laminations, and
wherein said stator wire windings are made of a high temperature magnet wire insulated with a vitreous enamel film bonded to the magnet wire, and the wire windings are bonded together with an electrically resistant adhesive made of a ceramic binder, and
wherein said rotor is separated from the wire windings in said stator by said thin-walled cylinder, thereby preventing debris from the stator windings from reaching the rotor,
wherein said motor is configured as a resolver, having an interior resolver rotor that carries laminations and windings for providing signal feedback information, said resolver rotor being mountable to a shaft extension of a brushless DC motor at a non-drive end thereof and providing an output signal that is directly proportional to an angle through which the resolver rotor moves, wherein the resolver rotor and stator are built up from a stack of magnetic-alloy laminations, wherein the resolver stator and rotor windings are made of a high temperature magnet wire insulated with a vitreous enamel film bonded to the magnet wire, and the windings are bonded together with an electrically resistant adhesive made of a ceramic binder.
2. A high temperature motor according to claim 1 , wherein the wire spools are manufactured from a ceramic material, and when wound with wire windings are inserted into the slots defining the stator's poles, thereby avoiding need for mica insulation and epoxy/adhesive between layers of windings.
3. A high temperature motor according to claim 1 , wherein said stator and said rotor are contained in a stator housing encased by a rear end cap and a front end cap, and a rear bearing for a rear end of the rotor shaft is mounted on an external side of the rear end cap, and a front bearing for a front end of the rotor shaft is mounted on an opposite external side of the front end cap, thereby reducing the possibility of debris from the stator and rotor migrating into the bearings' races.
4. A high temperature motor according to claim 1 , wherein said stator windings are made from high temperature magnet wire insulated with a vitreous enamel film fully cured at 1400°-1500° F.
5. A high temperature motor according to claim 1 , wherein said ceramic binder adhesive is selected to have properties of dielectric strength in the range of 270 volts/mil and volume resistivity of 10 ohm-cm at room temperature, and can maintain its high electrical resistance and dielectric strength even when exposed to very high temperatures.
6. A high temperature motor according to claim 1 , wherein said laminations are stamped from a cold rolled strip of a 49% Co-2% V-Fe soft magnetic alloy and final annealed in a protective atmosphere or vacuum environment at high temperature.
7. A high temperature motor according to claim 1 , wherein said magnetic alloy for said laminations is selected to have properties of a high magnetic saturation in the range of 24 kilogauss, high D.C. maximum permeability, low D.C. coercive force, and low A.C. core loss.
8. A high temperature motor according to claim 1 , further comprising bearings for the rotor having stellite races and ceramic balls coated with tungsten disulfide.
9. A high temperature motor according to claim 1 , wherein the high temperature magnet wire insulated with vitreous enamel film bonded together with adhesive ceramic binder of said stator windings, and the high temperature rare-earth permanent magnetic alloy of said stator and rotor laminations are selected and integrated together so that said motor can operate at least about 460° C. continuously for long durations.
10. A high temperature motor according to claim 1 , wherein the high temperature magnet wire insulated with vitreous enamel film is bonded together with the adhesive ceramic binder of said stator windings, and said stator and rotor laminations are made of high temperature rare-earth permanent magnetic alloy selected and integrated together so that said resolver can operate at least about 460° C. continuously for long durations.